Risk: You must be between 18 and 22 years of age to take advantage of these deals.

Buy an airline employee pass: Maybe you know a flight attendant or other airline employee who will let you buy a perks – the use of a friends-and-family pass. These are not free but a lot cheaper than a regular ticket.

Risk: There is no guarantee the flight you want will have room for you, especially since these passholders are typically given lowest boarding status for standby. An acquaintance recently racked up more than $400 in hotel and meal bills in a vain attempt to find a seat to her European destination. After trying for four days she eventually decided to cut her losses.

3. Red-eye flights

Risk: If your vacation time is short, do you really want to spend part of it too tired to enjoy yourself?

4. Destination cheating

Maybe you just want to fly one-way but you notice the round-trip flight is actually cheaper than one-way, so you buy the full ticket and discard the rest. Or you discover your destination is expensive, but notice it’s a stop along the way on another, cheaper flight so you buy that ticket and get off early. This is called throwaway ticketing and hidden city ticketing respectively and it is banned by most airlines – although people have been known to try it.

Risk: You could be stripped of your entire ticket – as well as your frequent flyer miles.